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The Skeletal System | Science Class 5 PDF Download

Introduction

  • Imagine if your body was made of jelly! How hard would it be to walk, run, or even stand straight? Luckily, we have something amazing inside us – bones!
  • Our bones form a strong framework called the skeletal system that keeps us standing tall, helps us move, and protects important organs like the brain and heart.
  • The skeletal system isn’t just about bones – it’s like a secret team working inside your body.
  • Each bone has a job, whether it’s holding you up, helping you play your favorite games, or keeping you safe from injuries.
  • And guess what? Your body has 206 bones by the time you grow up!

The Skeletal System | Science Class 5

  • The skeletal system protects its soft internal organs.
  • It provides shape to our body.
  • The bones are attached to the muscles and help in movement.
  • The skeletal system along with the muscular system, works together to make our body function like a perfect machine.
  • Let's learn more about the skeletal system.

The Skeletal System | Science Class 5

The Skeleton

  • The skeleton is the framework of bones that gives shape and strength to the body. 
  • It also protects our inner organs.
    The Skeleton protects the internal organs of the body
    The Skeleton protects the internal organs of the body
  • The bones help us in moving our body with the help of our muscles. 
  • There are 300 - 350 bones in an infant and 206 bones in an adult human being.
    The Skeletal System | Science Class 5
  • This decrease in the number of bones from the childhood to the adult stage is due to the fusion of some bones. 
  • Bones require calcium, phosphorus and some vitamins like vitamin D for proper development. 
  • Nerves that run through the bones also need blood supply. They are filled with soft fatty material called bone marrow.
    The Skeletal System | Science Class 5
  • The red blood cells in our blood are produced by the bone marrow.

Parts of Skeleton

The human skeleton consists of the skull, ribcage, backbone, limbs and girdle (pectoral and pelvic girdle).

The Skeletal System | Science Class 5

Parts of Human SkeletonParts of Human Skeleton

The skull

  • The bone of our head makes the skull. 
  • The cranium is a part of the skull that protects the brain. 
  • It is made up of eight flat bones, which are interlocked together. 
  • Except for the lower jaw, all the bones of the skull are fixed. The lower movable jaw enables us to eat and talk. 
  • The skull of an adult human generally contains 28 bones
  • Our face is made up of 14 bones, which protect important sense organs like the eyes, nose and tongue. 

Question for The Skeletal System
Try yourself:I protect the brain. I am made up of bones which are fused firmly together to form a shell-like structure. What am I?
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The backbone

  • The skull is attached to the backbone, which forms the main axis of the skeleton. 
  • The backbone is made up of 33 small bones called vertebrae
  • They are linked together to form a vertebral column. 
  • It protects the spinal cord and is also known as the spine
  • Our backbone is flexible and helps us to bend or twist. 

The Ribcage 

The Skeletal System | Science Class 5

  • Ribs are narrow curved bones. 
  • 12 pairs of ribs form a cage around the chest, which is called the ribcage
  • Ribs are joined to the backbone and the sternum
  • All 12 pairs of ribs are attached to the backbone but only 10 pairs of the ribs are attached to the sternum. 
  • Hence, the last two pairs of ribs are called floating bones. The ribcage protects the heart, lungs and other internal organs. 
  • The movement of the ribs also helps in respiration.

Question for The Skeletal System
Try yourself:Look at the given diagram carefully. 
The Skeletal System | Science Class 5 

Which are the organs that the above given bones protect?

(i) Stomach

(ii) Lungs

(iii) Liver

(iv) Heart

View Solution

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The Limbs

  • There are two pairs of limbs in our body — the fore limb and the hind limb. 
  • The fore limbs are called arms and the hind limbs are called legs.
  • The arms are attached to the backbone with the help of the shoulder girdles, also known as pectoral girdles.
    The Skeletal System | Science Class 5
  • The shoulder girdles consist of a pair of collarbones, a clavicle and a pair of shoulder blades, scapula
  • There are 27 bones in our hands and wrists, out of which the upper arm has a single long bone called the humerus, and the lower arm has two bones - radius and ulna together known as radio-ulna.

The Skeletal System | Science Class 5

  • The hind limb is attached to the bottom of the backbone with the help of the pelvic girdle
  • The upper part of the hind limb has a strong and powerful thigh bone called the femur
  • The femur is the longest bone of our body. 
  • The lower leg has two bones - tibia and fibula - together known as tibio fibula.  

The Skeletal System | Science Class 5

Girdles 

Our body has two types of girdles - pectoral girdle, also called shoulder girdle, and pelvic girdle, also called hip girdle. The girdles help in joining the limb directly to the backbone. The girdles are fixed to the backbone and lie on either side.

The Skeletal System | Science Class 5

Functions of the Skeletal System 

The skeleton has the following functions: 

  • The skeletal system gives shape, strength and support to the body. 
  • It protects the soft internal organs in the following ways:
    1. The skull protects the brain.
    2. The backbone protects the spinal cord.
    3. The ribcage protects the heart and the lungs.
    4. The hip bone protects organs like the kidneys and the bladder.
    5. The eyeballs are protected by the bony eye sockets. 
  • It helps to move our body with the help of the muscles. 
  • Red blood cells and white blood cells are produced in the bone marrow
  • Bones also store minerals like calcium and phosphorus.

Question for The Skeletal System
Try yourself:Look at the list below.

Collar Bone
Ribcage
Kneecap
Backbone

To which body system do the bones in the list belong to?

View Solution

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The Skeletal System
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What is a Joint?

A joint is a location in our body where two bones meet. It is a junction between two or more bones. It allows movement and provides mechanical support to the body.

The Skeletal System | Science Class 5

Cartilage is a type of elastic tissue, which keeps the bones from rubbing against each other. Bones are held together by strong tissues called ligaments. Our body has several joints. These joints may be movable or immovable. 

The Skeletal System | Science Class 5

Immovable Joints 

Bones are held tightly together in an immovable joint. Cartilages are not present between the joints. The bones in the skull are immovable joints. 

The Skeletal System | Science Class 5

Movable Joints 

  • The joints which allow different kinds of movements are called movable joints.
  • At joints, bones move smoothly because of a fluid that acts like a lubricant.
  • There are four types of movable joints.
  • Let us discuss them in detail.

1. Hinge Joint 
The Skeletal System | Science Class 5

This joint is like a hinge in a door. This kind of joint only allows back and forth, i.e, they allow movement in one direction only. Hinge joints are found in the elbow, knees, fingers, toes, etc. 

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2. Ball and Socket Joint 

The Skeletal System | Science Class 5

The ball and socket joint allow maximum movement. It is found in the hip and shoulder joints. In such a joint, one bone that ends in a ball fits into the socket of the other.

3. Pivot joint 

The Skeletal System | Science Class 5

The joint which joins the skull to the backbone is the pivot joint. The rod-shaped end of one bone fits into the ring-type end of the other bone. In this case, the rod-shaped vertebral column (first two vertebrae) fits into a hole in the skull. This joint allows movement of our head from side by side, and up and down. 

4. Gliding joint 

The Skeletal System | Science Class 5

This kind of joint is found between the wrist and ankle and between the two vertebrae. It allows slight movement in all directions. It helps our wrist to bend, twist and turn at each point.  

The document The Skeletal System | Science Class 5 is a part of the Class 5 Course Science Class 5.
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FAQs on The Skeletal System - Science Class 5

1. What are the main parts of the skeleton?
Ans. The main parts of the skeleton include the skull, spine (vertebral column), ribs, and limbs (arms and legs). The skeleton is made up of 206 bones in adults, which provide structure and support to the body.
2. What are the functions of the skeletal system?
Ans. The skeletal system has several important functions: it provides support and shape to the body, protects vital organs (like the brain and heart), allows for movement by serving as levers for muscles, stores minerals (such as calcium), and produces blood cells in the bone marrow.
3. What is a joint and why is it important?
Ans. A joint is a connection between two or more bones that allows for movement. Joints are important because they enable the body to move in various ways, such as bending, twisting, and rotating, which is essential for daily activities.
4. What are immovable joints?
Ans. Immovable joints, also known as fixed joints, are connections between bones that do not allow any movement. An example of immovable joints is the sutures in the skull, which keep the bones of the skull tightly connected.
5. What are movable joints and what types are there?
Ans. Movable joints are joints that allow for a wide range of movement. There are several types of movable joints, including hinge joints (like the knee and elbow), ball-and-socket joints (like the shoulder and hip), and pivot joints (like the neck). These joints enable activities like walking, running, and throwing.
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